This invention relates to a channel section for a scraper-chain conveyor.
Known scraper-chain conveyors, which are used primarily in underground mine workings, are constituted by a series of channel sections (or pans), which are connected together in an end-to-end relationship. The channel sections of one known type of scraper-chain conveyor have sigma-section side walls and a floor plate welded to the central portions of the side walls. Each of the side walls has inwardly-extending flanges at the top, the centre, and the base, the central flange being connected to the top and base flanges by means of a V-shaped wall section and by respective short vertical wall sections. The V-shaped wall sections define V-shaped grooves in the external surfaces of the side walls. The floor plate is welded to the central flanges of the sigma-shaped side walls.
A variety of devices for connecting the individual channel sections are known. Such devices normally resist tensile forces which tend to draw the ends of the channel sections apart; whilst permitting some angular mobility, in all directions, between the channel section ends. The connection devices are often subjected to very high forces during operation, not only the tensile forces which they are designed to resist, but also buckling forces tending to displace the conveyor ends laterally and/or vertically. Primarily, the lateral forces occur when the conveyor is advanced to follow up the mineral winning progress. This is usually accomplished by means of rams, which shift individual lengths of conveyor in a so-called "snaking" movement. The vertical forces usually occur when a mining machine supported on the conveyor is moved, for example, along the mineral face being won. Where the mine working is uneven, the lateral and vertical forces can increase substantially. Attachments, such as spill plates, and plough guides, are frequently bolted to the side walls of the channel sections. For this purpose, spill plate holders and guide plate holders are welded into the V-shaped grooves of the side walls.
One known way of connecting the individual channel sections of a scraper-chain conveyor is to provide interlocking coupling elements on the adjacent ends of each pair of adjacent channel sections. Each pair of interlocked coupling elements is connected together by means of screw bolts, so that the tensile forces can be transmitted between the channel section ends. The dimensions of the screw bolts that can be used for such connections are restricted by the dimensions of the V-shaped grooves in the channel section side walls. Unfortunately, this restriction on bolt size frequently results in the bolts being inadequate for the heavy loadings to which they are subjected. (see DE-OS No. 2 516 082).
It is also known to reinforce the side walls of the channel sections of a scraper-chain conveyor by welding stiffening members to the short vertical wall sections adjacent to the top and base flanges of the sigma-shaped side walls. The stiffening members lie flush with the top and base flanges, and also serve as backing members to which attachments such as spill plate holders and machine guides can be bolted. The stiffening members extend over substantially the entire length of the channel section side walls. Channel sections of this type are connected together by means of interlocking coupling elements and screw bolts. Here, the coupling elements are welded to the channel section side walls at the end portions thereof. The coupling elements also constitute stiffening members in these end portions where the longitudinal stiffening members are absent.
It is also known to join the interlocking coupling elements together by means of a toggle bolt (or dog-bone) connector. Such connector has an enlarged head at each end of a smooth shank. In this case, laterally-open recesses are provided in the coupling elements for receiving the connector. The connector is secured in place within the recesses in the coupling elements by means of removable retaining elements, such as C-shaped spring clips. Here again, the size of the connector is limited by the dimensions of the V-shaped grooves in the channel section side walls. Consequently, connections of this type may sometimes be inadequate to take up the heavy loadings which can occur. (see DE-OS No. 2 636 527).
The aim of the invention is to provide a scraper-chain conveyor channel section which does not suffer from the disadvantages of the known channel sections.